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\f0\fs48 \cf0 1. What is the purpose of categories ?\
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2. What is the difference between categories and extensions ?\
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3. What is difference between NSMutableString and NSString ?\
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4.What are properties ? What is the difference between property and instance variable ?\
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5. What is a class method ?\
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6. What is the purpose of protocols ?\
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7. What will happen when you send message to nil object ?\
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8. What are the four principles of OOP ?\
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9. Describe  the Encapsulation principle in OOP.\
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10.What is the purpose of initialisers ?\
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11. What is designated initialiser ?\
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12. What is the difference between class and object ?\
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13. What is the difference between Abstraction and Encapsulation ?\
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14. Why you would override a setter ? A getter ? \
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15. What is a polymorphism ?\
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16. What is the NSMutableDictionary used for ?\
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17. What is the time complexity of Merge Sort ?\
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18. What is the difference between passing by reference and by value ?\
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19. What is the difference between super and self keywords ?\
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20. What is inheritance ? Why would you use it ? \
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21. How to compare two objects ?\
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22. What is description method used for ?\
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23. What is a static variable ?\
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24. What is a global variable ?\
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25. What is extern used for ?\
}